Zelig: Everyone's Statistical Software

A framework that brings together an abundance of common
statistical models found across packages into a unified interface, and
provides a common architecture for estimation and interpretation, as well
as bridging functions to absorb increasingly more models into the
package. Zelig allows each individual package, for each
statistical model, to be accessed by a common uniformly structured call and
set of arguments. Moreover, Zelig automates all the surrounding building
blocks of a statistical work-flow–procedures and algorithms that may be
essential to one user's application but which the original package
developer did not use in their own research and might not themselves
support. These include bootstrapping, jackknifing, and re-weighting of data.
In particular, Zelig automatically generates predicted and simulated
quantities of interest (such as relative risk ratios, average treatment
effects, first differences and predicted and expected values) to interpret
and visualize complex models.